class_docstr: Computes the forward decoding in a linear-chain CRF.
code: def state_size(self):
      return self._num_tags
  
imports: import warnings
  import numpy
  import tensorflow
  from tensorflow_addons.rnn.abstract_rnn_cell import AbstractRNNCell
  from tensorflow_addons.utils.types import TensorLike
  from typeguard import typechecked
  from typing import Optional, Tuple
label_desc: Use image node_id 2 for calling the CrfDecodeForwardRnnCell obj's underlying member method code with example usage: obj.state_size() and returns: self